function isEmpty(obj){
	   if(obj==null || obj==undefined) return true;	  
	   if(obj.constructor.toString().match(/function Array()/)){
		  if(obj.length>0){
			  return false;
		  }else{
			  return true;
		  }
	   }else if(obj.constructor.toString().match(/function Object()/)){
		  var flag=true;
		   for(var key in obj){
			  flag= false;break;
		  } 
		   return flag;
	   }else if(obj.constructor.toString().match(/function String()/)){
		   if(obj==''){
			   return true;
		   }else{
			   return false;
		   }
	   }else{
		   throw Error(obj.constructor.toString()+" is not suitable for function isEmpty!");
	   }
   }